1. Field of the Invention
The invention relates to a method for encapsulating an electronic component, in particular a semiconductor, fixed on a carrier comprising the processing steps of: a) placing at least one foil layer in a mould, b) placing the carrier in contact with the foil layer with the side remote from the component, and c) encapsulating the electronic component with encapsulating material. The invention also relates to a foil for applying such a method.
2. Description of the Prior Art
The International patent application WO 00/66340 discloses a method for manufacturing encapsulated electronic components including the shielding of a side of the support of electronic components with an adhesive film. In a specific embodiment the adhesive film comprises an adhesive layer that becomes adhesive as a result of an increase in temperature of the film in the mould. This method has the problem that the duration of the processing step of moulding the electronic components includes the time to make the film adhesive, furthermore the level of adhesion of the film is difficult to control.
The encapsulating of electronic components, in particular semiconductor products, is a precisely controlled process wherein use is generally made of so-called transfer moulding. An object for (partial) encapsulation is herein placed in a mould. Liquid encapsulating material is forced into the mould by means of one or more plungers, wherein one or more mould cavities preformed in the mould are filled with encapsulating material. After curing of the encapsulating material the mould is opened and the product (partially) encapsulated with encapsulating material is taken out of the mould. In order to prevent the encapsulating material adhering to the mould, use is made in particular applications of an additional foil layer for placing in the mould. The encapsulating material is herein carried between the foil layer and the product for (partial) encapsulation. The encapsulating material thus remains separated from the mould.
When one or more housings manufactured from encapsulating material are arranged on a flat carrier, the encapsulating material can be forced unilaterally against the carrier and the opposite side of the carrier remains free of encapsulating material. In many products it is of great importance that this side remote from the encapsulating material remains free of encapsulating material, among other reasons because of the contact positions with which it must be possible to later connect the product for electrical conduction. However, an increasing number of products are being applied wherein the carrier is provided with openings/recesses through which, if specific measures are not taken, the encapsulating material can get to the side of the carrier which is to be kept clean. The solutions for preventing this are, among others, to apply the encapsulating material on one side in the still unopened position of the carrier followed by removal of a material layer from the carrier (for instance by means of etching) after the encapsulating material has been applied. It will be apparent that this includes additional treatments, which has the effect of increasing costs. A further solution in practice is, prior to applying encapsulating material, to adhere a protective layer against the carrier provided with openings. The openings in the thus treated (assembled) carrier are closed. The closed carrier can now be (partially) encapsulated. After the (partially) encapsulated carrier has been removed from the mould, the protective layer is removed from the carrier once again. A problem here is making the contact side of the (partially) encapsulated product properly clean again. This method also has the effect of considerably increasing costs.
The International patent application WO 00/66340 discloses a method for manufacturing encapsulated electronic components including the shielding a side of the support of electronic components with an adhesive film. In a specific embodiment the adhesive film comprises an adhesive layer that becomes adhesive as a result of an increase in temperature of the film in the mould. This method has the problem that the duration of the processing step of moulding the electronic components includes the time to make the film adhesive, furthermore the level of adhesion of the film is difficult to control.
The object of the present invention is to provide a method and means for encapsulating an electronic component, in particular a semiconductor, fixed on a carrier, wherein a contact side of the carrier is kept fee of encapsulating material in economic and controlled manner.